Equation with x to the denominator: ! The value of x must not reduce to zero the denominator !

Got it !

$\frac{3+2x}{1+2x}-\frac{5+2x}{7+2x}= 1- \frac{4x^2-1}{(7+2x)(1+2x)}$	$S = \{1 \} $
$\frac{2x}{x+10}-\frac{2(x-5)}{x+20}=\frac{160}{x+10}-\frac{150}{x+20}$	$S = \{80 \} $
$\frac{4x+5}{(2x-7)(x-1)}-\frac{3x}{x-1}=\frac{5}{2x-7}-\frac{3(x-2)}{x-1}$	$S = \{4 \} $
$5(\frac{9}{x-5)}-\frac{5}{x+5})-\frac{3(6x+5)}{x^2-25}=\frac{25}{x+5}$	$S = \{20 \} $